ACV will oxidize metal waterers, only use it in plastic. My waterers break down into two pieces. I keep a scrub brush and spray bottle full of diluted bleach by the hose. I scrub them twice a day usually and add a little ACV. I add the ACV by sight and smell. I think it's about two tbsp. My BF thinks I clean up after the animals too much. I'm starting to think he's right.